After a controversial vote this month to halt construction on a new middle school, the Upper Perkiomen school board reversed course Tuesday night and agreed to resume the $58 million project.

The 5-4 vote upended a tax revolt led by three new members of the board, who voted to pull the plug on the school three hours after being sworn into office Dec. 4.

James Glackin, one of the newcomers who earlier vowed to cancel the project, which foes said would send taxes soaring, switched sides, saying the district already had invested too much taxpayer money in the building to stop.

Voting with Glackin were Joan Smith, Mike Elliott, John Farris, and Judith Maginnis. Dissenting were Kerry Drake, Raeann Hofkin, and Melanie Cunningham and her son Steve Cunningham — who both won election to the board in November along with Glackin.

"I honestly was hopeful, but I really was not expecting that to happen," said Denise Campbell, among the 150 or so people who attended the meeting, many to demand that the new school be built.

The building would sit on a 43-acre property the district owns near Green Lane Reservoir. Site work is nearly completed and workers were starting to lay foundations, according to Superintendent Alexis McGloin.

Residents of the 3,200-student district in upper Montgomery County and a corner of Berks County had mounted an intense campaign to get Drake or Glackin to switch their votes, arguing in letters and social media that the district already had spent $8 million on building costs and that canceling construction contracts could lead to more wasted money and possibly lawsuits.

At the meeting, supporters wore green and carried signs "to make a visual impact to the board," Hope Manion, an advocate for a new school, said Wednesday morning.

School officials have said district schools are at capacity and enrollment is expected to grow. The middle school is 58 years old and has been renovated or expanded five times.

Opponents maintain that the plan was rushed through without a lot of input, and that the district needs to spend money on updating curriculum and hiring teachers instead of building facilities.

Residents said Glackin, a Philadelphia teacher, struggled with his decision and was criticized by some at the meeting for going back on his campaign promise.

"He was in a tight spot," said Manion. "We all crowded around and said, 'Thank you, thank you, you did the right thing.' We're now mobilizing emotional support. I said, if you do the right thing we'll be here to support you. It's hard to reverse yourself, but it was the right thing."

Neither Glackin nor Melanie Cunningham could be reached for comment Wednesday morning.